[Objective-C] Fix non-determinism in clang

[mgrang]

Summary

Iteration of the unordered Ivars causes objc-modern-metadata-visibility.mm (uncovered by reverse iterating SmallPtrSet).

[mgrang]

Ping for reviews please.

[dblaikie]

Sounds plausible to me

lib/Frontend/Rewrite/RewriteModernObjC.cpp

protected:
     SmallVector<ValueDecl *, 8> BlockByRefDecls;
     llvm::SmallPtrSet<ValueDecl *, 8> BlockByRefDeclsPtrSet;
     llvm::DenseMap<ValueDecl *, unsigned> BlockByRefDeclNo;
     llvm::SmallPtrSet<ValueDecl *, 8> ImportedBlockDecls;
     llvm::SmallPtrSet<VarDecl *, 8> ImportedLocalExternalDecls;
     
     llvm::DenseMap<BlockExpr *, std::string> RewrittenBlockExprs;
     llvm::DenseMap<ObjCInterfaceDecl *, 
-                    llvm::SmallPtrSet<ObjCIvarDecl *, 8> > ReferencedIvars;
+                    llvm::SmallSetVector<ObjCIvarDecl *, 8> > ReferencedIvars;
     
     // ivar bitfield grouping containers
     llvm::DenseSet<const ObjCInterfaceDecl *> ObjCInterefaceHasBitfieldGroups;
     llvm::DenseMap<const ObjCIvarDecl* , unsigned> IvarGroupNumber;
     // This container maps an <class, group number for ivar> tuple to the type
     // of the struct where the bitfield belongs.
     llvm::DenseMap<std::pair<const ObjCInterfaceDecl*, unsigned>, QualType> GroupRecordType;
     SmallVector<FunctionDecl*, 32> FunctionDefinitionsSeen;
void RewriteModernObjC::RewritePropertyImplDecl(ObjCPropertyImplDecl *PID,
   bool GenSetProperty = Attributes & (ObjCPropertyDecl::OBJC_PR_retain | 
                                       ObjCPropertyDecl::OBJC_PR_copy);
   if (GenSetProperty && !objcSetPropertyDefined) {
     objcSetPropertyDefined = true;
     // FIXME. Is this attribute correct in all cases?
     Setr = "\nextern \"C\" __declspec(dllimport) "
     "void objc_setProperty (id, SEL, long, id, bool, bool);\n";
   }
-  
   RewriteObjCMethodDecl(OID->getContainingInterface(), 
                         PD->getSetterMethodDecl(), Setr);
   Setr += "{ ";
   // Synthesize an explicit cast to initialize the ivar.
   // See objc-act.c:objc_synthesize_new_setter() for details.
   if (GenSetProperty) {
     Setr += "objc_setProperty (self, _cmd, ";
     RewriteIvarOffsetComputation(OID, Setr);

 }
 
 /// RewriteIvarOffsetSymbols - Rewrite ivar offset symbols of those ivars which
 /// have been referenced in an ivar access expression.
 void RewriteModernObjC::RewriteIvarOffsetSymbols(ObjCInterfaceDecl *CDecl,
                                                   std::string &Result) {
   // write out ivar offset symbols which have been referenced in an ivar
   // access expression.
-  llvm::SmallPtrSet<ObjCIvarDecl *, 8> Ivars = ReferencedIvars[CDecl];
+  llvm::SmallSetVector<ObjCIvarDecl *, 8> Ivars = ReferencedIvars[CDecl];
+
   if (Ivars.empty())
     return;
-  
   llvm::DenseSet<std::pair<const ObjCInterfaceDecl*, unsigned> > GroupSymbolOutput;
   for (ObjCIvarDecl *IvarDecl : Ivars) {
     const ObjCInterfaceDecl *IDecl = IvarDecl->getContainingInterface();
     unsigned GroupNo = 0;
     if (IvarDecl->isBitField()) {
       GroupNo = ObjCIvarBitfieldGroupNo(IvarDecl);
       if (GroupSymbolOutput.count(std::make_pair(IDecl, GroupNo)))
         continue;

test/Rewriter/objc-modern-metadata-visibility2.mm

+// REQUIRES: abi-breaking-checks
+// NOTE: This test has been split from objc-modern-metadata-visibility.mm in
+// order to test with -reverse-iterate as this flag is only present with
+// ABI_BREAKING_CHECKS.
+
+// RUN: %clang_cc1 -E %s -o %t.mm -mllvm -reverse-iterate
+// RUN: %clang_cc1 -x objective-c++ -fblocks -fms-extensions -rewrite-objc %t.mm -mllvm -reverse-iterate -o - | FileCheck %s
+// rdar://11144048
+
+@class NSString;
+
+@interface NSObject {
+    Class isa;
+}
+@end
+
+@interface Sub : NSObject {
+    int subIvar;
+    NSString *nsstring;
+@private
+    id PrivateIvar;
+}
+@end
+
+@implementation Sub
+- (id) MyNSString { return subIvar ? PrivateIvar : nsstring; }
+@end
+
+@interface NSString @end
+@implementation NSString @end
+
+// CHECK: __declspec(allocate(".objc_ivar$B")) extern "C" __declspec(dllimport) unsigned long OBJC_IVAR_$_Sub$subIvar;
+// CHECK: __declspec(allocate(".objc_ivar$B")) extern "C" unsigned long OBJC_IVAR_$_Sub$PrivateIvar;
+// CHECK: __declspec(allocate(".objc_ivar$B")) extern "C" __declspec(dllimport) unsigned long OBJC_IVAR_$_Sub$nsstring;
+// CHECK: #pragma warning(disable:4273)
+// CHECK: __declspec(allocate(".objc_ivar$B")) extern "C" __declspec(dllexport) unsigned long int OBJC_IVAR_$_Sub$subIvar
+// CHECK: __declspec(allocate(".objc_ivar$B")) extern "C" __declspec(dllexport) unsigned long int OBJC_IVAR_$_Sub$nsstring
+// CHECK: __declspec(allocate(".objc_ivar$B")) extern "C" unsigned long int OBJC_IVAR_$_Sub$PrivateIvar
+// CHECK: extern "C" __declspec(dllimport) struct _class_t OBJC_METACLASS_$_NSObject;
+// CHECK: extern "C" __declspec(dllexport) struct _class_t OBJC_METACLASS_$_Sub
+// CHECK: extern "C" __declspec(dllimport) struct _class_t OBJC_CLASS_$_NSObject;
+// CHECK: extern "C" __declspec(dllexport) struct _class_t OBJC_CLASS_$_Sub
+// CHECK: extern "C" __declspec(dllexport) struct _class_t OBJC_CLASS_$_NSString;
+// CHECK: extern "C" __declspec(dllexport) struct _class_t OBJC_METACLASS_$_NSString
+// CHECK: extern "C" __declspec(dllexport) struct _class_t OBJC_CLASS_$_NSString